Carbon nanotubes (hereinafter abbreviated as “CNT”) are a new material that is attracting attention in numerous fields due to their superior electrical conductivity, thermal conductivity, mechanical strength and other properties. In general, CNT are synthesized by subjecting carbon or a raw material containing carbon to high-temperature conditions in the presence of a catalyst, as necessary. Known examples of commonly used production processes include arc discharge, laser ablation and chemical vapor deposition. Among these, chemical vapor deposition (CVD) synthesizes CNT by thermally decomposing a raw material containing carbon (carbon source). Examples of prior art documents relating to the production of CNT by using CVD include Patent Documents 1 to 3. Patent Document 1 relates to a technique for producing CNT with a fluidized bed that uses a catalyst and a fluidizing agent. In addition, Patent Document 2 relates to a technique for synthesizing CNT by contacting a solid catalyst with a carbon-containing gas in the presence of a fluidizing agent and fluidizing the solid catalyst. Patent Document 3 relates to a technique for producing CNT using camphor as the carbon source.
On the other hand, carbon materials having various diverse forms, including the above-described CNT, are used in various applications. Typical examples include fibrous carbon materials (namely, carbon fibers) and particulate carbon materials having a diameter of 0.1 mm or more or microparticulate carbon materials having an even smaller diameter (such as carbon black). Although carbon materials per se possess characteristics attributable to being composed of carbon, such as superior electrical conductivity, thermal conductivity, acid resistance and mechanical strength, composite materials that further improve upon the various properties of carbonaceous materials are desired for use in various industrial fields (such as the aircraft industry, the battery and other electronic device industries, the health care industry and the architecture and civil engineering industries).
One aspect of these composite materials that is currently attracting attention includes structural composite materials in which carbon nanotubes are caused to be present (and typically, supported) on the surface of a carbonaceous base material or a base material of another organic substance or an inorganic substance. Since carbon nanotubes have high electrical conductivity, low wear and other industrially advantageous properties (for example, absorption of hydrogen and lithium ions) due to their unique microscopic structure, composite materials (such as carbon materials) offering higher levels of performance than in the past are expected to be developed by using these carbon nanotubes. For example, Patent Documents 4 and 5 describe prior art examples of composite materials composed of carbon nanotubes and a carbonaceous base material.
The production of such composite materials is first premised on the need to enable CNT to be present in a suitable state on the surface of a target base material (such as by bonding or adhering). However, since processes that enable CNT to be efficiently formed on a base material (such as a carbonaceous base material) have yet to be developed with any of the above-described processes, composite materials utilizing the above-mentioned properties of CNT are expensive and difficult to provide. For example, the above-mentioned Patent Documents 4 and 5 as well as Patent Document 6 describe examples of the prior art relating to processes for producing CNT.